"His number is 666."
Revelation chapter 13, verses 15-18: "The second beast was given power to give breath to the image of the first beast, so that it could speak and cause all who refused to worship the image to be killed. He also forced everyone, small and great, rich and poor, free and slave, to receive a mark on his right hand or on his forehead, so that no one could not buy or sell unless he had the mark, which is the name of the beast or the number of his name. This calls for wisdom. If anyone has insight, let him calculate the number of the beast, for it is man's number. His number is 666."
Above are actual verses from the bible and they are alarming. There will be a "beast" coming that will demand to be worshiped by the whole world on the penalty of death. When you find that a new technology arrives that let's people get a mark on hand or forehead to be used for their shopping and trading, please, open up the bible and read how you can have eternal life and escape the coming judgment – the very judgment that begins with Jesus Christ returning to earth and finishing off all those who opose him. There is not even going to be a fight, only death and decay. Listen to the song that describes Jesus' return to earth.
[Note: This mark on hand or forehad may, of course, also be interpreted symbolically/figuratively and does not necesarily have to be understood literally. After all, this is a prophetic text with tons of allegories!)